Chemical Properties
copper chromite is a black, tetragonal powder that is insoluble in water. It is prepared by the heating to 400°C of copper(II) chromate(VI).
Physical properties
Grayish-black tetragonal crystals; density 5.4 g/cm
3. When heated to elevated temperatures (above 900°C) copper(II) chromite decomposes to cupric chromate(II), CuCrO
2 and chromium (VI) oxide, CrO
3. Copper(II) chromite is insoluble in water and dilute acids.
Uses
Copper chromite is used as a hydrogenation catalyst.
Application
Copper chromite is primarily used as a catalyst forhydrogenation reactions because of its ability to hydrogenate functional groupsin aliphatic and aromatic compounds selectively. Industrially, copper chromiteis used to reduce furfural to furfuryl alcohol and butyraldehyde to 1-butanol,partially reduce conjugated dienes to monoenes, and selectively reduce carbonylgroups in vegetable oils. This CuCr catalyst is studied for a variety ofcatalytic applications including converting the hydrogenolysis of cellulose.It is also used as a catalyst for combustion to help control burn rate and as alight-absorbing pigment.
Preparation
Copper(II) chromite is obtained by heating copper chromate, CuCrO
4 at 400°C. The Adkin catalyst, a mixture of copper oxide and copper chromite, is prepared by mixing aqueous solutions of copper nitrate, sodium dichromate and ammonium hydroxide; the orange precipitate of copper ammonium chromate formed is dried and then heated below 400°C.
General Description
Copper chromite is a black powder and inorganic pigment thatadopts a spinel crystal structure. It can be made by the high-temperaturecalcination of copper(II) oxide and chromium(III) oxide or the thermaldecomposition of copper chromate, which evolves oxygen at higher temperaturesand decomposes to copper chromite.
